Treatment of hydrocarbons



Patented Dec. 26,1944

TREATMENT or nrnnoomons Julian M. Mavity, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, Ill., a corporation of Delaware No Drawing. Application September 28, 1942, Serial No. 459,962

Claims.

. This is a continuation-impart of my co-pending application Serial No. 363,684, filed October 31, 1940.

This invention relates to the treatment of hy-' drocarbons of substantially motor fuel boilin range having low antiknock value such as straight-run gasolines and naphthas from paraffinic and naphthenic crude oils or thermally cracked gasolines to improve their antiknock characteristics. The process isalso applicable to low boiling hydrocarbons produced from hydrocarbon materials generally, including synthetic oils derived from lignites, coals, and shales.

More specifically, the invention has reference to a catalytic reforming process which utilizes operating conditions-under which no substantial amount of strictly pyrolytic reactions occur. The catalysts are particularly effective in dehydrogenation and also cycli'zation reactions, and are of importance because their refractory nature enables them to retain their catalytic properties 7 tion of the double bonds, the degree of saturation of the straight chain and cyclic hydrocarbons,

and the presence of other substances in minor amounts. which influence the rate of combustion of the uel. Although the antilmock value'may be increased in part as a, result of the loss of hydrogen, various other reactions may also occur such as isomerization involving the formation of branched chain hydrocarbons either saturated or unsaturated and the shifting of double bonds. or cyclization and aromatization involving the formation of hydrocarbons of a cyclic character with or without parafiinic and unsaturated side chains.

In one specific embodiment the invention comprises the reforming treatment of-hydrocarbon oils boiling substantially within the motor fuel boiling range and having low antiknock value whereby said hydrocarbons are vaporized and sub-' jected to contact with a catalyst comprising essentially an intimate mixture of specially prepared titanla supporting an oxide of molybdenum whereby a motorfuel of high antiknock value is obtained.

According to the present invention, hydrocar bon fractions boiling substantially within the motor fuel boiling range are contacted with a specific catalyst so as to increase the octane number as the result of various hydrocarbon conversion reactions such as cyclization, lsomerization, dehydrogenation, hydrogen transfer, desulfurization, and to a, minor extent carbon-to-carbon cleavage reactions. In general, paraffinic and naphthenic hydrocarbons are dehydrogenated to produce olefinic and aromatic hydrocarbons, and more or less isomerization takes place with the shifting of double bonds and the branching of less branched chain hydrocarbons.

As previously noted, the oxides of molybdenum used are supported on a titanium oxide carrier. It is necessary that the carrier for a suitable catalyst be of a refractory material which will not sinter or fuse under the high temperature conditions of use and regeneration when in prolonged service in'tne reform ng of the hydrocarbon oils. It is also necessary that the carrierbe adaptable to the activating oxides of molybdenum so as to mutually provide the catalytic surfaces promoting the above mentioned desired reactions. The t1- tanium oxide used as a carrier is preferably in a relatively pure state and may be obtained from rutile, illmenlte, or other titanium-contammg material. Themanuracture thereof is generally known, particularly in connection with the manufacture of paints wher titanium oxide has one of its main uses. Titanium oxide prepared as a impregnating components is used, the density of the catalyst is increased and the porosity is decreased with a subsequent reduction of catalytically available surface. In the case of molybdic oxide various proportions may be used with good results, such as from 2 to weight per cent of molybdena with respect to titania. Lower and higher percentages of the molybdena may give lower catalytic activity.

In the impregnating step, ammonium molybdate may be dissolved in water to form a solution used to deposit the desired amount of oxides of molybdenum on the surface and in the pores of th titanium oxide particles after suitable heating. .In addition to the molybdenum compounds impregnated in the catalyst, a small proportion of stabilizing agent may also be impregnated in the catalyst particles. It has been found that in the prolonged use of thi type of catalyst, there is a gradual dropping off of activity due to a change in form of the active material. It has also been found that this tendency can be coun- 0 teracted by adding small amounts of compounds leading to the formation of metal oxides. more particularly oxides such as those of mainesium and zinc.

The titanium oxide carrier may be impregquently heatedin air at a temperaturejof approximately 500 C. to decompose and remove the lubricant. The pelleted material is then impregnated with av solution of the molybdenum compound.

The titanium oxide carrier may also be shaped into particles by other methods such as extrusion or pressing with subsequent granulation and the particles thus formed impregnated similarly as above. The activating oxides of molybdenum or compounds from which they are produced may also be incorporated into the carrier before it is shaped into particles in which case the heating and calcmation after shaping into particles removes any lubricant which may be employed and may also convert the impregnated material into the desired active form for reaction.

The catalyst particles are suitably employed in beds and the hydrocarbons to be treated are vaporized and contacted with the catalyst beds at regulated temperature, pressure and time conditions. The temperature of the catalyst bed is so regulated as to compensate for the endothermlc and exothermic conditions occurring of these deposits as before indicated so as to avoid heating the catalyst to unnecessarily high temperatures which may "gradually reduce its activity. Various means such as regulating the oxygen concentration in the gases and the volume of said gases or removing heat by heatabsorbing means are the more common methods employed.

The hydrocarbon oil fraction which is to be processed is vaporized and subjected to contact with the above catalyst at a temperature of the order of 450-700" C. and under a pressure from substantially atmospheric to approximately 500 pounds or more per square inch. The rate at which the hydrocarbon vapors are passed over the catalyst may vary from approximately 0.1 to 40 volumes of liquid charge per hour per volume of catalyst space in the reactor.

The titanium oxide supported catalyst is not restricted to use-as particles in a granular mass since the catalyst can be used as a finely divided powder and contacted with the vapor or disposed in a stream of the hydrocarbon oil to be reformed, and processed under suitable conditions of temperature, pressure and contact time to produce large yields of the desired high antiknock gasoline. The powdered catalyst may then be separated from the high antiknock gasoline and from the adhering oil by various procedures, and the separated catalyst regenerated by removing hydrocarbonaceous deposits by solvent treatment and/or heating in the presence of air or oxygencontaining gases in order to remove the deposited material. The regenerated catalyst is then used either alone or'in mixture with fresh catalyst suspended in the hydrocarbon oil or vapors processed.

The following specific example is given to illustrate the process, a method of catalyst preparation also being given. The process should not be considered'as limited to the example nor to the particular catalyst preparation since these are given merely as illustrations of the novelty and utility of the invention.

The titanium dioxide carrier for the catalyst of the following example is very finely divided titanium dioxide of approximately 99% purity and having an average particle size between 1 and microns. The dry carrier is mixed with a small amount of a hydrogenated vegetable oil lubricant to facilitate pelletmg and is xormed into V by V inch cylindrical pellets. The pellets are calcined at a temperature of approximately 500 C. to remove the lubricant. After cooling, the pellets are impregnated with a solution of ammonium molybdate in suflicient proportion and concentration to give ultimately a catalyst having the approximate composition of 8% M00: and 92% TiOz. The impregnated pills are then dried and calcined at a temperature of approximately 500 C.

A Mid-Continent straight run naphtha having an endpoint of approximately 205 C. and an octane number of 41 is vaporized and preheated to a temperature of approximately 575 C. and contacted with the above described molybdenumtitania catalyst disposed in a reactor at substantially atmospheric pressure using a liquid space velocity of approximately 1.49. The treated vapors are then condensed and 205 C. endpoint gasoline and gas separated from the products.

The recovered motor fuel corresponds to 87 volume percent of the naphtha charged to the process and has an octane number of 67 by the motor method. I

I claim as my invention:

1. A process for dehydrogenating hydrocarbons boiling in the gasoline range which comprises subjecting said hydrocarbons to dehydrogenating conditions in the presence of a catalyst comprising a major proportion of titanium oxide and a minor proportion of molybdenum oxide.

2. A process for treating hydrocarbons of approximately-motor fuel boiling range to increase the antiknocl: value thereof which comprises contacting said hydrocarbons with a catalyst 'comprising titanium oxide and molybdenum oxide at dehydrogenating conditions.

3. A process for reforming a naphtha fraction to increase the antiknock value thereof which comprises contacting said fraction at a temperature of from about 450 to about 700 C. and

presence of molybdenum oxide supported on titanium oxide. I

JULIAN M. MAVITY. 

